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Dr. Kimberly Sue: Xylazine in street drugs

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Xylazine, a veterinary sedative that can be deadly to humans, is turning up in street drugs across the country.

On Tuesday, August 15, 2023, SciLine interviewed: Dr. Kimberly Sue, an assistant professor of medicine with the program in addiction medicine at Yale University School of Medicine. She discussed topics including: what is known about the spread of xylazine throughout the street drug supply; the health effects and risks of xylazine; treatments for people who have taken xylazine; how the mixing of xylazine into opioids complicates opioid overdose prevention; and the Biden administration’s declaration that fentanyl mixed with xylazine is an emerging threat to the United States, and plan to reduce xylazine-related deaths by 15% compared to 2022.

Declared interests:

Dr. Sue was previously the medical director of the National Harm Reduction Coalition. She has no other conflicts of interest. 

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KIMBERLY SUE: My name is Dr. Kimberly Sue. I’m an addiction medicine doctor and an assistant professor of medicine at Yale University School of Medicine. And I study harm reduction. I study drug treatment. And I study gender and women.

Interview with SciLine

What is harm reduction?


KIMBERLY SUE: So, harm reduction has many definitions. But a basic definition in the addiction medicine field is a wide ranging set of practical strategies and ideas aimed at reducing the negative consequences associated with behaviors like substance use or sex work.

What is xylazine?


KIMBERLY SUE: Xylazine is a veterinary tranquilizer. It’s not approved for human use in the United States. It’s commonly used in animal surgeries as a sedative, as a pain reliever and a hypnotic.

What is known about the spread of xylazine through the street drug supply?


KIMBERLY SUE: From what we do know xylazine has been expanding in the U.S. street drug supply over the past five years or so. We know that it’s up in all U.S. census tracts. But that varies depending on the region. It also depends on if people are even capturing that data. So, there was a recent study that came out in the last one or two years, which showed that xylazine increased in the rates of overdose deaths from less than 1% to 6.7% over the course of the last five years—so, from 2015 to 2020. So, it’s increased substantially, but depending on what region you’re in and if we’re keeping access to that data, it could be very different. So, for example, we know that xylazine is more prevalent in states like Pennsylvania, Maryland, and Connecticut, where they’ve been keeping the data for a long time. Less is known about the West, the Southwest, and the South.

What are the effects of xylazine and the risks of taking it?


KIMBERLY SUE: Xylazine in humans—again, with the caveat that we do not 100% know about the actual effects of xylazine in humans because it has not been formally studied—is that it does cause—clinically it causes low blood pressure, it causes central nervous system depression, which means that it sedates you or it can decrease your drive to breathe. And it can also decrease your heart rate. There are a couple other things that can cause, like changes in your blood sugar, but the main effects are the low blood pressure and the fact that it sedates you quite significantly. So, those are some of the things that we’re worried about when we’re seeing xylazine in overdoses or we’re seeing it mixed with other substances—because those things can potentially kill you.

What treatments exist for people who have overdose on xylazine?


KIMBERLY SUE: So, there is no known or approved antidote for xylazine in humans at this time. There are some for animals, but those are not approved for use in humans. We do recommend that if you encounter someone who has a xylazine overdose or a suspected xylazine overdose that you give them naloxone, or Narcan, as you might do if you encountered someone experiencing an opioid overdose, and call 911 and get some emergency medical services and care. We do know that if you go to the hospital, you might need support for ventilation or for breathing. The paramedics or the doctors in the emergency room might intubate you and take over your breathing. And they might have to give you blood pressure medicine support to keep your blood pressure up because xylazine can decrease your blood pressure causing what we call hypotension which can be pretty serious and pretty dangerous if not treated.

How does the mixing of xylazine into opioids complicate opioid overdose prevention?


KIMBERLY SUE: The arrival of xylazine in the drug supply, it does change some things about responding to opioid overdoses and some things it does not change. We do recommend that you respond to a potential xylazine-opioid overdose that is mixed with—responding with support for airway and administering naloxone or the brand name Narcan. So, those things have not changed. Xylazine is not an opioid, and xylazine is not expected to come off the brain receptors if you use naloxone or Narcan. That’s the same thing as alcohol. It’s the same thing as other substances like benzodiazepines, such as Klonopin or Xanax that people might have used. But we do recommend that since it’s largely present in the drug supply as an add on, or adulterant, to fentanyl or other opioids, that you do try to reverse any potential component for an opioid overdose because that could save someone’s life. So, we do again recommend that you call for additional assistance because like I said, there’s no known antidote for xylazine—people might need to be monitored. People might need reversal agents for other substances that they have on board as well.

What can you tell us about wounds associated with xylazine use?


KIMBERLY SUE: My patients describe that in one or two days, an area where they may have injected becomes black, it becomes necrotic. And then it grows into—it can really become confluent into a much larger wound that can be a larger part of the body surface area, of the skin. And it can have varying levels of healing and harm. So, we do suspect that these wounds are from—the local blood supply in the area goes down because of xylazine. So, vasoconstriction is a medical term. But also I suspect that there’s something locally toxic about xylazine that is causing this damage. And they themselves are not necessarily infected, but they are at risk of infection especially if these wounds get larger. So, they get larger and the skin is your natural barrier against infection.

When do xylazine-related wounds occur?


KIMBERLY SUE: It has been some controversy about if you can get the wounds from sniffing or snorting xylazine in a substance. And largely, in my patient experience, I have only seen it in people who are injecting fentanyl with xylazine, for example. And we are not sure—this is an area for further research, again, very important research, about if these wounds are coming up from other routes of administration of using drugs.

Do you have any thoughts on the federal government’s actions with regards to xylazine?


KIMBERLY SUE: I’ve been pretty happy to hear that the Biden administration has drawn attention to the xylazine problem. Xylazine, like you said, is increasingly prevalent. It’s increasingly part of the fentanyl supply. We need much more funding for research on this—research on it in humans, understanding of the basic epidemiology. We do not know how prevalent it is in all states. We do not commonly have money or support to test for xylazine. And so all of these things are really important as we try to take care of people who have xylazine overdoses or xylazine-related wounds. It is pretty important to not further criminalize xylazine, to schedule it in the Controlled Substances Act, in my opinion. We do know from previous efforts with other substances like fentanyl that criminalizing it, sending people to prison in jail for it, it does not help. In fact, it only harms people who are suffering from substance use disorders. And those are people who are often experiencing a lot of poverty. They’re experiencing a lot of structural barriers that make them predisposed to be caught up in the criminal legal system.

Do you have any advice for reporters covering xylazine, substance use, and overdoses?

[Posted August 15, 2023 | Download video]